Yes. He is old! I'm not trying to convince you that flying in the OT would be a good thing. I'm just pointing out that the logic you are using to say that it's bad in the OT is the same logic you (and Lucas) ignore when saying it's perfectly fine in the PT. And, if you take PT era logic, Obi-Wan's not even that old. He's in his 50s now, according to the official timeline, which is much younger than he was originally supposed to be. But Count Dooku is at least as old in the PT as Obi-Wan is in the OT. And Christopher Lee is definitely old enough that he had to have a stunt double do most of his fighting for him. So why is it okay to have Dooku jumping around like a maniac but not old Ben? The answer: it's not.